As the consumer electronics industry continues to mature, and the capabilities of processors increase, more devices have become available for public use that allow the transfer of data between devices and more applications have become available that operate based on their transferred data. Of particular note are the Internet and local area networks (LANs). These two innovations allow multiple users and multiple devices to communicate and exchange data between different devices and device types. With the advent of these devices and capabilities, users (both business and residential) increasingly desire to transmit data from mobile locations.
The first widespread deployment of a protocol to deal with these issues, was Internet Protocol version 4 (IPv4) in the early 1980's. IPv4 is a network layer protocol used to provide unique addressing to ensure that two computers communicating over the Internet can uniquely identify each other. IPv4 has a 32-bit addressing scheme which allows for 232 (approximately 4.2 billion) potentially unique addresses. This limit of 232 addresses is becoming a bottleneck as the need for more unique addresses will arrive in the foreseeable future. Additionally, IPv4 was not specifically designed to be efficient for mobile users. In fact, when IPv4 was implemented there were not a lot of mobile consumer devices that could communicate across the Internet as there are today. In this context, mobile IP equipment can be considered to be any a piece of equipment that is moveable, e.g., a laptop computer, cell phone or a Personal Digital Assistant (PDA), and that crosses boundaries between different networks while desiring to maintain connectivity or be allowed to connect to a foreign network. Accordingly, as this need and the need for more IP addresses developed, Internet Protocol version 6 (IPv6) was created and is now being implemented.
IPv6 uses a 128-bit addressing scheme which allows for 2128 unique addresses, i.e., significantly more addresses than are provided for in IPv4. The addressing scheme in IPv6 is composed of two parts: a 64-bit host part and a 64-bit sub network prefix (subnet prefix). IPv6 is also more mobile friendly than IPv4, particularly with the addition of Mobile IPv6 (MIPv6).
Mobile IP version 4 (Mobile IPv4, Mobile IP, MIPv4 or MIP) and the current version of Mobile IPv6 (MIPv6) are built to provide mobility to a host or Mobile Node (MN). The other nodes, usually referred to as Correspondent Nodes (CN), are usually seen as fixed hosts although they can also be mobile. Reference is now made to FIG. 1, which shows a MIPv6 network architecture 100 as suggested by the current MIPv6 specification found in an Internet Engineering Task Force (IETF)'s Request For Comment (RFC) number 3775. As can be seen in FIG. 1, an IP network 100 comprises a MN 110 in communication with a CN 150.
The MN 110 has a permanently assigned, 128-bit home address valid in its home network 115, which home address is allocated upon initialization of the MN 110 in the home network 115. The home address comprises a subnet prefix, which is 64-bit long, and an interface identifier, which is also 64-bit long. The allocation mechanism is well-known in the prior art. The MN 110 is further in communication with a Home Agent (HA) 140 located in its home network 115 (via 125). Among other functionalities, the HA 140 keeps record of a foreign address of the MN 110 valid outside the home network 115. The foreign address is called Care-of-Address (CoA) in the context of MIPv6, and also comprises 128 bits. The CoA assigned to the MN 110 changes in time as the MN 110 moves from one network to another. The record kept by the HA 140, referred to as binding in the context of MIPv6, ties the CoA to the home address. A Binding Cache Entry (BCE) comprising the home address and the CoA of the mobile node is also kept in the CN 150 for the purpose of reaching the MN 110. The HA 140 is also responsible for routing traffic received at the home address to the MN 110. The traffic received is forwarded by the HA 140 on a link 145 toward the MN 110.
The MIPv6 concept in a typical situation is described below. The MN 110 is in bidirectional IP session (via 155), with the CN 150. When the MN 110 moves from a first home network to a visited network, as illustrated by arrow 135 in FIG. 1, the MN 110 acquires a first CoA. This modification in addressing state of the MN 110 must be advertised to the CN 150. In order to advertise the acquisition of its first CoA, the MN 110 sends a first binding update (BU), comprising the HoA, the first CoA and a 64-bit sequence number (SQN), to the CN 150. The CN 150, upon reception of the first BU creates a BCE for the session, where it stores the HoA, the first CoA and the SQN. The CN 150 then sends a first binding acknowledgement (BA) to the MN 110. Reception of the first BA at the MN 110 indicates a successful completion of the advertisement of the modification of the addressing state.
MIPv6, therefore, provides a stable identifier (a Home Address) to a mobile node (MN) while it is moving between multiple IP networks. This is established by mapping the home address (HoA) into a Care-of-address (CoA) that is the current topological address of the mobile node. This mapping is performed either by the Home Agent (HA) in the bidirectional tunneling mode or by the node which is talking to the mobile node, the correspondent node (CN), in the Route Optimized (RO) mode.
Moreover, in MIPv6, the MN is responsible for signaling to its home agent to enable session continuity as the MN moves between networks. The mobile node controls the mobility management. This signaling utilizes scarce radio resources (such as the link between the MN and a network for example). Furthermore, not all nodes may be capable of supporting MIPv6.
According to one method described in the IETF PMIPv6 draft entitled Proxy Mobile IPv6, another network node can be used as a proxy mobile agent for the mobile node in order to allow nodes incapable of (or, unwilling to perform) MIPv6 to enjoy the benefits of mobility. The proxy mobile agent can perform the mobility signaling on behalf of the mobile node. Another advantage of using a proxy agent in a radio access network is that the MIPv6 signaling does not use the scarce radio resources (over the link between the MN and a network for example). The proxy mobility agent (PMA) is a functionality that can be implemented within an access router (AR) through which the MN communicates to the network.
The above described solution, however, does not facilitate an optimal path for transmitting data packets between a mobile node and correspondent nodes. The proxy mobile agent can be used to reduce latency in communication of data packets between a mobile node and correspondent nodes. Accordingly, exemplary embodiments described below address the need for reducing the latency in communicating data packets between a mobile node and Correspondent nodes over a network.